PBR material : how to use a RMA file in Blender?
You don't need the height map for this.. the normal map will work fine (make sure to add the vector Normal Map and make the image texture non-color).

The RMA works like this.. add the RMA image texture and then add a "Separate RGB" node.  Each channel in the RMA is an input into your BSDF shader.  Most of the time it's this...


Red = Ambient Occlusion (you can add this with a multiply on your Base Color if you want)
Green = Roughness
Blue = Metalic


I know this is an old question but maybe this will help others as this comes up early on Google for RMA and Blender.